Documenting how to view `Modelfile`s (#723)

* Documented viewing Modelfiles in ollama.ai/library

* Moved Modelfile in ollama.ai down per request

docs/modelfile.md

@@ -41,6 +41,8 @@ INSTRUCTION arguments
 
 ## Examples
 
+### Basic `Modelfile`
+
 An example of a `Modelfile` creating a mario blueprint:
 
 ```modelfile
@@ -63,6 +65,35 @@ To use this:
 
 More examples are available in the [examples directory](../examples).
 
+### `Modelfile`s in [ollama.ai/library][1]
+
+There are two ways to view `Modelfile`s underlying the models in [ollama.ai/library][1]:
+
+- Option 1: view a details page from a model's tags page:
+   1. Go to a particular model's tags (e.g. https://ollama.ai/library/llama2/tags)
+   2. Click on a tag (e.g. https://ollama.ai/library/llama2:13b)
+   3. Scroll down to "Layers"
+      - Note: if the [`FROM` instruction](#from-required) is not present,
+        it means the model was created from a local file
+- Option 2: use `ollama show` to print the `Modelfile` like so:
+
+  ```bash
+  > ollama show --modelfile llama2:13b
+  # Modelfile generated by "ollama show"
+  # To build a new Modelfile based on this one, replace the FROM line with:
+  # FROM llama2:13b
+
+  FROM /root/.ollama/models/blobs/sha256:123abc
+  TEMPLATE """[INST] {{ if and .First .System }}<<SYS>>{{ .System }}<</SYS>>
+
+  {{ end }}{{ .Prompt }} [/INST] """
+  SYSTEM """"""
+  PARAMETER stop [INST]
+  PARAMETER stop [/INST]
+  PARAMETER stop <<SYS>>
+  PARAMETER stop <</SYS>>
+  ```
+
 ## Instructions
 
 ### FROM (Required)
@@ -177,3 +208,5 @@ LICENSE """
 
 - the **`Modelfile` is not case sensitive**. In the examples, we use uppercase for instructions to make it easier to distinguish it from arguments.
 - Instructions can be in any order. In the examples, we start with FROM instruction to keep it easily readable.
+
+[1]: https://ollama.ai/library